The invention relates to a process and an apparatus for monitoring the activity of catalytic reactors located in the exhaust system of internal combustion engines. The monitor signals are taken from exhaust gas sensors located at the inlet and outlet ends of the catalytic reactor.
Catalytic reactors are used for exhaust gas detoxication in internal combustion engines. They are inserted in the exhaust systems of these engines and their activity must be monitored. The lifetime of catalytic reactors is highly dependent on the temperature and the total gas throughput which, in turn, depend on the operational states and conditions of the internal combustion engine. In addition, the lifetime of catalytic reactors is affected by poisons, for example by lead, sulphur or phosphorus which may be present in the fuel. These effects may change the capacity of the catalyzer to convert toxic material, and when the conversion of toxic materials falls below a predetermined limit, the engine may not be usable under the prevailing regulations.
A known apparatus for monitoring the activity of catalyzers includes two exhaust gas measuring sensors. One of these exhaust gas sensors is installed at the inlet and the other at the outlet of the catalyzer and they measure the oxygen concentration of the exhaust gas at the inlets and outlets of the catalyzer, respectively. The difference of these two signals is a measure of the activity or performance capacity of the catalytic reactor. The described system operates with sufficient accuracy only in certain operational domains and it is quite difficult to determine what these domains are.